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Monoelemental Two-Dimensional Iodinene Nanosheets: a First-Principles Study of the Electronic and Optical Properties
No full textVery recently, two-dimensional (2D) iodinene, a novel layered and buckled structure has been successfully fabricated (Qian et al 2020 Adv. Mater. 32 2004835). Motivated by this latest experimental accomplishment, for the first time we conduct density functional theory, first-principles calculations to explore the structural, electronic, and optical properties of monolayer, few-layer and bulk iodinene. Unlike the majority of monoelemental 2D lattices, iodinene is predicted to be an intrinsic semiconductor. On the basis of calculations using the generalized gradient approximation of Perdew-Burke-Ernzerhof for the exchange-correlation functional and the Heyd-Scuseria-Ernzerhof (HSE06) functional, it is shown that the electronic bandgap of iodinene decreases with increasing the number of atomic layers. Our HSE06 results reveal that the bandgap of iodinene decreases from 2.08 to 1.28 eV as the number of atomic layers change from one to five, highlighting the finely tunable bandgap. The optical study shows the monolayer has the ability to absorb a wide range of ultraviolet light, more than multilayers and bulk iodinene. As the number of layers increases, the absorption spectra exhibits a blue shift relative to monolayer iodinene. This study confirms the remarkable prospect for the application of iodinene in nanoelectronics and optoelectronics owing to its intrinsic semiconducting nature.This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea Government (MSIT) (NRF-2015M2B2A4033123).National Research Foundation of Korea (NRF) - Korea Government (MSIT) [NRF-2015M2B2A4033123
Mini Sinif Elektrikli İnsansiz Hava Araçlari için Batarya Kapasitesi Kestirimi
No full textRechargeable secondary batteries; It has been introduced to the market as economical and long-lasting alternatives to primary batteries in order to meet the portability needs of electronic devices such as mobile phones and laptops. Today it powers all kinds of electrically powered systems, from aircraft to automobiles. Secondary batteries, the ability to be recharged, also brought safety weaknesses such as easily burning and bursting when forced beyond their limits. In order to use rechargeable batteries safely and efficiently, battery management systems that can instantly monitor and control their status are in operation. Battery management systems continuously measure the current and voltage from the terminal of a battery under load by means of sensors. It prevents excessive discharge and very high current draw during discharge of the battery. Likewise, it works to prevent overcharging and charging with high current during charging. Apart from preventing going beyond the limits during charging, it is also responsible for the balanced charging of cells in the battery pack obtained by connecting more than one cell in series or parallel. Battery management systems, in addition to the task of providing safety; It runs estimation algorithms to calculate the instantaneous capacity, health, remaining life of the battery. Among the battery situations that are tried to be estimated, the battery capacity stands out as a very critical parameter for the vehicle using the battery to make the appropriate planning before starting its mission and to determine the appropriate strategy during the mission. In the literature to calculate the battery capacity; There are Coulomb counter, open circuit voltage estimation, electrochemical impedance spectroscopy, electrical equivalent circuit models, electrochemical cell models, adaptive filter based estimation or artificial intelligence based estimation methods. In this study, the hardware and real-time software of the estimator were prepared and tested on a fixed wing electric motor driven unmanned aerial vehicle. Since the estimation algorithm runs on a microcontroller in real time, the Kalman filter, which is an adaptive filter-based estimation method, has been applied, taking into account the trade-off between accuracy, sensitivity and complexity among the proposed estimation methods. In order to measure and test battery model parameters, a laboratory environment was established and simulation studies were carried out. The battery estimator hardware on the aircraft was verified by flight test and the results were evaluated.Yeniden doldurulabilir ikincil bataryalar; cep telefonu, dizüstü bilgisayar gibi elektronik cihazların, taşınabilirlik ihtiyacını karşılamak amacıyla birincil bataryaların ekonomik ve uzun ömürlü alternatifleri olarak piyasaya çıkmış olsa da günümüzde hava araçlarından otomobillere kadar elektrikle çalışan her türlü sisteme güç vermektedir. İkincil bataryalara, yeniden doldurulabilme yeteneği aynı zamanda limitlerinin dışına zorlandığında kolayca yanma ve patlama gibi güvenlik zafiyetini de beraberinde getirmiştir. Yeniden doldurulabilir bataryaları güvenli ve verimli olarak kullanmak amacıyla durumunu anlık olarak izleyen ve kontrol edebilen batarya yönetim sistemleri görev yapmaktadır. Batarya yönetim sistemleri, sensörler vasıtasıyla yük altındaki bir bataryanın terminalinden akımını, gerilimini sürekli olarak ölçer. Bataryanın deşarjı esnasında aşırı boşalmasını ve çok yüksek akım çekilmesini önler. Aynı şekilde şarj esnasında da aşırı şarj olmasını ve yüksek akım ile şarj edilmesini engellemek için çalışmaktadır. Şarj esnasında limitlerin dışına çıkılmasını önlemek dışında, birden fazla hücrenin seri ya da paralel bağlanması ile elde edilmiş batarya paketinde, hücrelerin dengeli olarak şarj edilmesinden de sorumludur. Batarya yönetim sistemleri, güvenliği sağlama görevinin yanı sıra; bataryanın anlık kapasitesi, sağlığı, kalan ömrü gibi durumlarını hesaplamak için tahmin algoritmaları çalıştırmaktadır. Tahmin edilmeye çalışılan batarya durumları içerisinden batarya kapasitesi, bataryayı kullanan aracın görevine başlamadan önce uygun planlamayı yapabilmesi ve görev esnasında uygun stratejiyi belirleyebilmesi için oldukça kritik bir parametre olarak ön plana çıkmaktadır. Batarya kapasitesini hesaplamak için literatürde; Coulomb sayacı, açık devre gerilim tahmini, elektrokimyasal empedans spektroskopi, elektriksel eşdeğer devre modelleri, elektrokimyasal hücre modelleri, uyarlamalı filtre temelli kestirim ya da yapay zekâ temelli tahmin yöntemleri bulunmaktadır. Bu çalışma kapsamında, kestiricinin donanımı ve gerçek zamanlı yazılımı hazırlanarak, sabit kanatlı elektrik motor tahrikli insansız hava aracı üzerinde denenmiştir. Tahmin algoritmasının gerçek zamanlı olarak bir mikrodenetleyici üzerinde koşması sebebiyle, önerilen tahmin yöntemlerinden, doğruluk hassasiyet ve karmaşıklık takası göz önünde bulundurularak, uyarlamalı filtre temelli kestirim yöntemi olan Kalman filtresi uygulanmıştır. Batarya model parametrelerinin ölçülmesi ve test edilmesi amacıyla laboratuvar ortamı kurulmuş ve benzetim çalışmaları yapılmıştır. Hava aracı üzerinde bulunan batarya kestirici donanımının uçuş testi ile doğrulaması yapılarak sonuçları değerlendirilmiştir
Crack Propagation in the Double Cantilever Beam Using Peridynamic Theory
No full textCoker, Demirkan/0000-0001-7385-7089; Guler, Mehmet/0000-0002-1159-556XIn this study, Peridynamic (PD) theory is used to model mode-I delamination in unidirectional and multi-directional laminated composites. Experiments are conducted to determine mode-I fracture toughness in a unidirectional carbon-epoxy Double Cantilever Beam (DCB) specimen where the crack propagation remains on the original notch plane. The PD model of the DCB geometry is generated using an in-house pre-processor code in MATLAB and implemented in ABAQUS software. The brittle damage law in the original PD model is modified to a bilinear law to capture progressive softening. PD results are found to be in good agreement with the experimental results in terms of force-displacement curves and crack length. Next, this PD approach is applied to a multidirectional angle-ply DCB specimen. The PD model shows that delamination path jumps between the layers as the delamination grows. Force-displacement behaviour and delamination patterns obtained using PD model are compared with the corresponding experimental results from Gong et al. (2018). As a result, PD theory with bilinear softening law is found to successfully capture force-displacement relations and delamination migration in multidirectional laminated composites under mode-I loading conditions.Scientific and Technological Research Council of Turkiye (TUBITAK) [115M585]This study is funded by the The Scientific and Technological Research Council of Turkiye (TUBITAK) under Grant No. 115M585. The authors acknowledge RUZGEM (METU Center for Wind Energy) Structures and Materials Laboratory for the use of testing facilities, and CES composites for manufacturing of test specimens
Görsel İletişim Tasarımı Bölümü Stüdyo Derslerinin Uzaktan Eğitim Modeli ile Gerçekleştirilmesinde Yaşanan Sorunlar ve Çözüm Önerileri
No full textThis research aimed to determine the situations that arise during the implementation of design studio courses in undergraduate programs of visual communication / graphic design departments of universities with online learning from distance, its effect on student success and to make suggestions for the improvement and development of this method. In this context, our research has been designed to deal with the advantages and disadvantages of realizing studio lessons with online education from distance, to have information about the efficiency of the system and its effect on student success both through interviews and a case study. The data obtained were arranged in sub-headings and themes in line with the sub-purposes of the research. Suggestions were also presented for the results of the research, which reflected on the findings with both positive and negative aspects of the online education method.Bu araştırma, üniversitelerin görsel iletişim/grafik tasarımı bölümleri lisans programlarında yer alan tasarım stüdyo derslerinin uzaktan çevrimiçi eğitim yöntemiyle gerçekleştirilmesi sürecinde ortaya çıkan durumları belirlemeyi, öğrenci başarısına etkisini ve bu yöntemin iyileşmesi ve geliştirilmesi için önerilerde bulunmayı amaçlamıştır. Bu bağlamda araştırmamız stüdyo derslerinin uzaktan çevrimiçi eğitim yöntemiyle gerçekleştirilmesinin avantaj ve dezavantajları ile ele alınması, sistemin verimliliği hakkında bilgi sahibi olunması ve uzaktan çevrimiçi eğitim yönteminin öğrenci başarısına yönelik etkisi hem gerçekleştirilen görüşmeler hem de bir örnek uygulama çalışması üzerinden konuya ilişkin ayrıntılı bir analiz ortaya çıkarılması üzerine tasarlanmıştır. Elde edilen veriler araştırmanın alt amaçları doğrultusunda alt başlıklar ve temalar halinde sıralanmıştır. Uzaktan çevrimiçi eğitim yönteminin hem olumlu hem de olumsuz pek çok farklı yönleriyle bulgulara yansıyan araştırmanın sonuçlarına ayrıca öneriler de sunulmuştur
Self-Regulation Under Asymmetric Cost Information
No full textIn this paper, we study how a monopolistic firm with unknown costs may behave under the threat of regulation. To this aim, we integrate the self-regulation model of Glazer and McMillan (Q J Econ 107(3):1089-1099, 1992) with the optimal regulatory mechanism devised by Baron and Myerson (Econometrica 50(4):911-930, 1982) for the case of asymmetric information. Simulating the equilibrium outcome of our integrated model for a wide range of parameter values, we show among many results that the firm threatened with regulation always constrains its price; moreover, the price the firm charges under the threat of regulation can be even lower than the price it has to charge when it is regulated
A Fast Polarization Estimation Method With Convolutional Neural Networks
No full text9th IEEE International Workshop on Metrology for AeroSpace, MetroAeroSpace 2022 -- 27 June 2022 through 29 June 2022 -- -- 182210In this study, we propose a new method with an artificial intelligence infrastructure to estimate polarization of a radar signal. In modern electronic warfare and radar systems polarization of the return signal now poses essential information. Subspace-based algorithms such as MUSIC and ESPRIT have high computational costs for estimating polarization. Computational cost and performance analysis of the proposed method is conducted via simulations and results are discussed along with the existing solutions such as MUSIC algorithm. Simulation results show that the proposed algorithm reduce the computational cost compared to classical MUSIC. The proposed algorithm also reduce the polarization estimation error in low SNR scenarios. © 2022 IEEE
Genetic Algorithm Based, On-Chip, Fishbone Grating Waveguide and Transition Design for Time-Domain Operation
No full textConference on Integrated Photonics Platforms II -- APR 03-MAY 20, 2022 -- ELECTR NETWORKThe limited bandwidth of conventional phase-shifter-based antenna arrays, which is caused by steering in different angles at different frequencies named as the beam-squint effect, is a problem that should be taken into consideration for the ultrawide band systems. To overcome this problem, designing optical true time delay (TTD) lines for the antenna arrays is crucial for the development of next-generation, wideband communication, and imaging systems, which employ short pulses for wideband operation. One of the important problems for employing such short pulses is the dispersion during the propagation along the on-chip optical waveguides, which cause the distortion in the pulse shape and decrease in the amplitude of the pulse. Therefore, we propose a one-dimensional (1D) fishbone grating waveguide with a Lego type of step taper on silicon-on-insulator (SOI) substrate, both of which are designed for time-domain operation. The designed grating waveguide/taper pair is excited by a pulsed Gaussian light source, having a FWHM of 90 fs at a center wavelength of 1550 nm, where we investigate the possibility of controlling the dispersion by using SiO2 cladding modulation and taper structure optimization using genetic algorithm. The simulation results show that it is possible to decrease the dispersion in terms of the amplitude of the pulse up to 85%. The simulation results also show that the coupling efficiency from the taper to the waveguide can be increased up to 73%, which also decrease the dispersion of the pulse significantly. The simulated bandwidth of the grating waveguide/taper pair is found to be 56 nm, which allows ultrawide band operation.H.A.G. acknowledges the partial support from the Scientific and Technical Research Council (TUBITAK) 2210A Grant. This project is funded by TUBITAK 119E501.SPIE,IdEx Univ Strasbourg,CNRS,ICube,Univ StrasbourgScientific and Technical Research Council (TUBITAK) [2210A]; TUBITAK [119E501